You’ve accidentally broken a file and need to restore it from an earlier commit without touching anything else in your repository. Here’s how. Restore a file to a specific commit To restore my_file.name to its state at a specific commit: git checkout commit_sha1 my_file.name Replace commit_sha1 with the actual commit hash. You can find it…
Over time, internal and external links on your site inevitably break — pages get deleted, domains expire, content moves. Finding and fixing these broken links improves user experience and helps with SEO, since search engines penalize sites with dead links. Automated Checking Tools Several web-based tools can scan your site and report broken links: https://www.brokenlinkcheck.com/…
When you work with multiple git servers or need different credentials for different hosts, SSH’s config file lets you specify which key to use for each server. This is cleaner than managing aliases or environment variables. Setting Up ~/.ssh/config Create or edit ~/.ssh/config and add entries for each server: Host git.example.org Port 22111 IdentityFile ~/.ssh/id_rsa.git.example.org…
By default, libvirt stores VM images as files in /var/lib/libvirt/images/. While functional, this approach limits flexibility. LVM (Logical Volume Management) provides better control over disk space, snapshots, and performance tuning. Using LVM volumes as libvirt storage pools lets you manage VM storage like block devices rather than files, giving you faster provisioning, atomic snapshots, and…
When your OCaml program crashes with Fatal error: Exception “Stack_overflow” but doesn’t tell you where the problem originated, you need to enable backtrace reporting. The process is straightforward but requires recompilation. Enable Debug Symbols and Backtraces First, recompile your program with the -g flag to include debug information: ocamlopt -g -o myprogram myprogram.ml If you’re…
sbt (Scala Build Tool) isn’t available in the default Fedora repositories, though Scala itself is. Here’s how to install it properly. Using the Official Repository The most reliable approach is to add sbt’s official repository to your system. This gives you automatic updates and avoids manual RPM downloads. Create the repository configuration file: sudo tee…
If you have emails stuck in Evolution’s local directory structure that you want to move to an IMAP account via Thunderbird, you’ll need to convert them to a format Thunderbird can import, then push them to your mail server. Step 1: Prepare Your Evolution Mail Directory Evolution typically stores mail in a Maildir format with…
utop is an improved OCaml REPL with line editing, history, context-sensitive completion, and syntax highlighting. While powerful, its key bindings differ from standard GNU readline, which can be jarring if you’re used to standard shell behavior. Getting the key bindings list The simplest way to see all available bindings is to run the #utop_bindings directive…
Trailing spaces and tabs at the end of lines are common annoyances in source code and configuration files. They’re invisible, waste space, and can cause issues with certain tools or version control systems. Here’s how to remove them efficiently. Using sed The most straightforward approach with sed: sed ‘s/[[:space:]]*$//’ your_file > your_file.tmp && mv your_file.tmp…
Vim’s default OCaml indentation is limited and doesn’t handle the language’s syntax well. You’ll want to use ocp-indent, a dedicated indentation tool built specifically for OCaml that understands the language’s scoping and structure rules. Installing ocp-indent First, install the tool via OPAM (OCaml Package Manager): opam install ocp-indent If you don’t have OPAM installed, install…
When you need to format an integer with leading zeros in bash, printf is the standard approach. This is useful for generating zero-padded IDs, filenames, or any formatted output. Using printf The basic syntax mirrors C’s sprintf: n=42 str=$(printf “%08d” “$n”) echo “$str” # Output: 00000042 Here, %08d means: %d — format as decimal integer…
When you need to execute a system command and capture its output in C, popen() is the standard approach. Unlike system(), which just runs a command, popen() gives you a file stream connected to the command’s stdout or stdin. Basic Usage The popen() function signature is: FILE *popen(const char *command, const char *type); The type…
Start by compiling your C source files into object files: gcc -c lib1.c lib2.c This produces lib1.o and lib2.o. You can use any compiler flags here—-Wall, -O2, -fPIC, etc.—that match your build requirements. Position-independent code (-fPIC) isn’t strictly required for static libraries but is good practice if you anticipate reusing these objects elsewhere. Creating the…
Amazon’s Kindle Library web interface forces you to delete books one at a time through the UI. If you’ve accumulated hundreds of items, this becomes tedious. Here are practical approaches to bulk-delete from your Kindle Library. Browser Console Method The most straightforward approach uses your browser’s developer console to run deletion scripts directly against Amazon’s…
Working with environment variables in C is straightforward using POSIX APIs. The two primary functions are getenv() for retrieval and setenv() for modification. Getting Environment Variables Use getenv() to read an environment variable: #include <stdlib.h> #include <stdio.h> int main(void) { const char *path = getenv(“PATH”); if (path != NULL) { printf(“PATH: %s\n”, path); } else…
C++ provides the <iomanip> header for controlling how data appears when printed to standard output. These manipulators give you precise control over formatting, alignment, precision, and radix. Basic Manipulators The most common manipulators are persistent (they remain active until changed) or stateless (they apply once and reset). Width and Alignment: #include <iostream> #include <iomanip> int…
Designated initializers for aggregate types with non-trivial members (like std::vector) have inconsistent support across GCC versions. This error typically appears when you try to initialize a struct containing standard library containers using designated initializer syntax in the wrong order. The Problem When you compile this code with older GCC versions: struct Stat { vector<int> vec;…
There are several reliable methods to generate random strings of a specific length in bash. The choice depends on your character set requirements and use case. Using tr with /dev/urandom The tr command combined with /dev/urandom is the most portable and straightforward approach: tr -dc “[:alpha:]” < /dev/urandom | head -c 10 This produces a…
Cron is a minimal execution environment. Unlike your interactive shell, cron runs with a stripped-down environment containing only a few variables like PATH, MAILTO, and SHELL. Any variables you’ve defined in your shell profile won’t be available unless you explicitly source them in your crontab entries. The Problem If your cron job depends on environment…
When you need to populate PDF forms with large datasets, manual entry becomes impractical. Scripting this process saves time and eliminates human error. Here’s how to automate PDF form filling using Python. Understanding PDF Form Filling PDF forms contain field names that can be programmatically populated. The process typically involves: Identifying field names in your…